I am considering buying a new 7 series or 8 series. I have never had a BMW but believe these cars have run flat tires. How many miles can I expect from a set of these tires? I live in Florida (US) and drive 18,000 highway miles a year.
Like with EPA fuel economy... you mileage may vary.
The M850i has staggered tires. That means no front-to-back rotating. The driven wheels on a two-wheel-drive car will wear more. With BMW xDrive, the power is split about 60-40. So, the M850i's rear tires will still wear faster than the front, but the difference will be less than with a RWD car.
RFT's tend to wear faster than non-RFT's, because they concentrate the wear on the inside and outside of the contact patch. You can stop this by overinflating them. But, that makes the car ride and handle horribly.
Performance tires wear faster because the rubber is "stickier." It's sort of like one of those really good white-rubber pencil erasers, sticky means fast wear.
Throw in almost 600 h.p. for the M850i, and maybe 4300 pounds of curb weight and you have the perfect storm for tire wear. Unless you're driving Miss Daisy around, plan on replacing tires every... oh, let's see... 18k miles or once a year. The good news is that tires are cheap... trivial, actually... compared to what you'll be paying in depreciation.
Highway miles are easier on tires though. So, you might get 25k miles if you're lucky.
I have high-performance, non-RFT's on my 4100 pound, 300 h.p. 535i. I also have a square set-up (all tires the same size), rotate my tires, and practice "tire whispering" (adjusting the pressure for even tire wear). Doing all this, I'll get between 35k and 40k miles out of my tires. I'll get 55k to 60k miles out of the non-RFT, square set-up, SUV (low performance) tires on Frau Putzer's X3 30i xDrive.
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